In recent years, in the field of electronic devices, there have been added requirements of long-term reliability, flexible shape, and enabling curved display in addition to light weight and large size. The used of a film substrate such as a transparent plastic has been started in place of a glass substrate having a heavy weight and difficult in making a large size.
However, a film substrate such as a transparent plastic has a problem of inferior gas barrier property compared with a glass substrate.
It has been known that the function of the electronic device will be deteriorated by the penetrated water vapor and oxygen gas when a substrate of inferior gas barrier property is used.
It has been generally known to use a gas barrier film produced by forming a film having a gas barrier property (a gas barrier layer) on a film substrate. For example, as a gas barrier film used for package material for an object required to be provided with or for a liquid crystal display element, there are a film composed of a film substrate on which silicon oxide or a aluminum oxide is vapor deposited.
It has been reported that a light extraction structure containing a light scatter layer is efficient for the purpose of improving light-emission efficiency of an organic EL (electroluminescence) element (one of electronic devices) (refer to Patent document 1, for example).
When a gas barrier layer or a light scatter layer is formed on a film substrate, it will be produced unevenness on the surface. As a result, when a light-emitting unit having organic functional layers is formed thereon, it may be occurred deterioration of keeping property or short-circuit (electric short) under the environment of high-temperature and high-humidity.
In the first place, it is known that an organic EL element is very sensitive to a small amount of water, oxygen and other organic compounds (such as a remaining solvent). It was proposed a structure having a gas barrier layer directly under an organic functional layer (refer to Patent document 2, for example). It may be a reasonable idea.
However, it has not been disclosed technology to achieve both gas barrier property and bend (curvature) repeating resistance, namely, flexible aptitude. This has not been realized until now.